Prig (noun)

A person who is excessively concerned with propriety and correctness, especially in matters of social conduct.

Origin:

Origin of the word is uncertain. it first appeared in the early 18th century.

Examples:

1. His constant criticism of others' manners made him the office prig.
2. She always seemed to be on high horse, acting like a prig.
3. He was seen as a prig, always trying to correct people's grammar.
4. His priggish attitude made it hard for him to make friends.
5. The prig refused to attend the party because he deemed it to be improper.